It is expected that a long term evolution-advanced (LTE-A) system, which is the standard of the next generation wireless communication system, will support a coordinated multi point (CoMP) system and a multi user-MIMO (MU-MIMO) system, which have not been supported by the existing standard, so as to improve a data transmission rate. In this case, the CoMP system means that two or more base stations or cells perform communication with a mobile station by coordinating with each other to improve communication throughput between the base station (cell or sector) and the mobile station located in a shaded zone. Examples of the CoMP system may include a coordinated MIMO type joint processing (CoMP-JP) system through data sharing and a CoMP-coordinated scheduling/beamforming (CoMP-CS) system. According to the joint processing (CoMP-JP) system, the mobile station may simultaneously receive data from each base station that performs CoMP, and may improve receiving throughput by combining the signals received from each base station. Unlike the joint processing system, according to the coordinated scheduling/beamforming (CoMP-CS) system, the mobile station may momentarily receive data from one base station through beamforming. The MU-MIMO technology means that the base station allocates each antenna resource to different mobile stations and selects and schedules a mobile station that enables a high data transmission rate per antenna. This MU-MIMO system is to improve system throughput.
Also, the next generation LTE-A system is designed to enable large scaled data transmission. The LTE-A system adopts the carrier aggregation (CA) technology to perform data transmission by aggregating a plurality of component carriers (CCs), whereby a transmission bandwidth of the mobile station may be improved and usage efficiency of the frequency may be increased. The LTE-A system may extend the bandwidth to reach 100 MHz by simultaneously using a plurality of carriers (that is, multiple carriers) in group not a single carrier used in the existing LTE Rel-8/9 system. In other words, the LTE-A system has re-defined a carrier, which is defined to reach maximum 20 MHz in the existing LTE Rel-8/9 system, as a component carrier and has allowed one mobile station to use maximum five component carriers (CCs) through the carrier aggregation technology.
Under the circumstances that the CA technology is introduced and a plurality of timing advance (TA) groups exist, if a PUSCH, PRACH, PUCCH and SRS are simultaneously transmitted through the plurality of TA groups, a method for determining whether to transmit or drop a sounding reference signal (SRS) has not been suggested up to now.